# 跟练链接 B 站的
# https://www.bilibili.com/video/BV1P14y1L7kP/?p=2&spm_id_from=333.880.my_history.page.click&vd_source=ffde1e6c5946d5428a8146c8880b2bc9

# 计算数字的阶乘
shuru = int(input("请输入你要的数字："))
num = 1

# for i in range(1, shuru + 1):
#     num = num * i

while shuru > 1:
    num = num * shuru
    shuru = shuru - 1

print(num)
